Field of the Invention
The present invention relates to a honeycomb type heating device which is installed in an exhaust gas emitting path for an exhaust gas emitted from an engine of an automobile or the like and increases a temperature of an exhaust gas purifying catalyst to a catalyst activating temperature at an early timing and relates to a method of using the same.
Description of the Related Art
Hitherto, a honeycomb structure having a catalyst loaded thereon is used in order to purify a toxic material such as HC, CO, and NOx contained in an exhaust gas emitted from an engine of an automobile or the like. In this way, when the exhaust gas is treated by the catalyst loaded on the honeycomb structure, the temperature of the catalyst needs to be increased to the catalyst activating temperature. However, since the temperature of the catalyst does not reach the catalyst activating temperature at the start-up of the engine, a problem arises in that the exhaust gas is not sufficiently purified. Particularly, since a plug-in hybrid vehicle (PHEV) or a hybrid vehicle (HV) uses only a motor in a travel mode, the engine is not frequently started, and the temperature of the catalyst is low during the start-up of the engine. For this reason, the exhaust gas purifying performance is easily degraded immediately after the start-up of the engine.
In order to solve this problem, there is proposed an electric heating catalyst (EHC) in which a temperature of a catalyst is increased to a catalyst activating temperature before the start-up of an engine while an electrode is disposed in a honeycomb structure formed of conductive ceramics and a current is supplied to the honeycomb structure so that heat is radiated from the honeycomb structure (see Patent Document 1).
Further, there is also proposed a heating device in which a tubular resistance heating heater is disposed so as to surround a circumferential wall of a honeycomb structure and a wall surface of the circumferential wall of the honeycomb structure is heated so as to transfer heat to an inner cell structure (see Patent Document 2).
[Patent Document 1] JP-A-2010-229976
[Patent Document 2] JP-A-2013-238116